Comment on the Chou-Yang model for elastic scattering

The Chou-Yang model forpp elastic scattering, modified to include the effect of coupled inelastic channels, is used to fit recent data in the region of the dip, i.e., 1.0≦|t|≦2.0 (GeV/c)² for incident momenta ranging from 35 to 250 GeV/c. Good quantitative agreement is found for an inelastic coupling which is predominantly real, as compared to the mostly imaginary elastic coupling. Implications for dips at highert, which are predicted by the model but as yet not observed experimentally, are discussed.     

Technology showcase electronic penetrometer for field tests

The design and construction of a cone penetrometer for field use is described. The penetrometer is mounted on a frame to which two wheels are fitted for towing the device from one test site to the next. An electric motor drives the penetrometer during the test and simultaneous readings are performed of both cone depth and penetration resistance. The device weighs 70 kg and the maximum force on the cone typically exceeds 1.2 kN. The acquired data are transferred to a microcomputer and after each penetration the result is presented to the operator in graphic form. The microcomputer is equipped with a fairly large RAM memory which serves as storage medium for data during measuring work. Afterwards, data are easily moved to a mainframe computer for analysis.     

Electron-transfer reactions and conformational changes associated with the reduction of substituted bianthrones

The electrochemical reduction of several substituted bianthrones is similar to that of the parent compound. 3,3′-Dimethylbianthrone (II), 3,3′-di-n-heptylbianthrone (III). 3,3′-dimethoxybianthrone (IV) and 1,1′-dimethylbianthrone -(V) were studied in dimethylformamide using cyclic voltammetry and transmission mode spectroelectrochemistry. For each compound the low temperature A form is reduced in a two-electron irreversible reaction to a twisted dianion, B^2?. Upon oxidation, B^2? forms first B, then B, whose spectral properties are identical to those of the high-temperature thermochromic form of the bianthrones. Rate constants for the B-A reaction were determined for each compound. The reduction of 2,3,2′,3′-dibenzo-7,7′-dimethylbianthrone (VI) showed somewhat different features which were tentatively interpreted in terms of redox catalysis.     

The effect of sintering on the mineralogy of a synthetic heavy mineral concentrate base prepared by mixing together specpure oxides

Synthetic heavy mineral concentrate standards for calibrating a d.c. arc emission spectrometer were prepared from specpure oxides and compounds. X-ray diffraction and scanning electron microscope studies of the heat-treated synthetic matrix showed that minerals which occurred in natural heavy mineral concentrates were formed. An optimum sintering time of 4 hr was established by monitoring X-ray diffraction peaks of minerals undergoing alteration or being formed in the synthetic base.     

Anomalous low energy Kα lines in Al and Si from high energy oxygen bombardments

Three prominant peaks are observed in Kα X-ray spectra of both Al and Si at energies below the characteristic Kα_1,2 lines. These emission lines were produced by 30 MeV oxygen bombardment and recorded with a crystal spectrometer. The exact origin of these lines is not understood.     

Modeling chlorite-iodide reaction dynamics using a chlorine dioxide-iodide reaction mechanism

The mechanism of Lengyel, Li, Kustin, and Epstein (J. Am. Chem. Soc. 1996, 118, 3708) for the oscillatory chlorine dioxide-iodide reaction accurately models the reaction in closed and open systems. We investigated whether this mechanism minus the single reaction involving chlorine dioxide models the chlorite-iodide reaction equally well. It agrees qualitatively with clock reaction results. As for open system dynamics, the mechanism predicts the existence of two steady states and bistability in very nearly the same regions where these features are found experimentally in the pH range 2-4. A discrepancy in the range of bistability emerges as pH decreases, and it cannot be remedied by taking into account chlorous acid decomposition. That we were unable to locate an oscillatory region is of greater significance. Because the chlorite-iodide reaction is sensitive to mixing effects, we incorporated a two-parameter model of imperfect mixing but still found no oscillations at physically reasonable parameter values. These discrepancies strongly suggest that to obtain predictive utility for the chlorite-iodide reaction, revision of the chlorine dioxide-iodide mechanism is required.     

Solitary wave interaction

The interaction between solitary wave solutions to a double sine-Gordon equation is examined numerically. Depending on the velocity, formation of breather-like modes or quasi solitonic behaviour are observed when a 2δ-kink interact with a 2π-antikink. As a result of collision between a (2π-2δ)-kink and a (2π-2δ)-antikink two 2δ-kink-antikink pairs always appear.     

Threshold electron impact excitation of argon in the region of the M1 edge

The threshold electron impact spectrum of argon has been obtained in the energy range 24–35 eV using the sulphur hexafluoride electron scavenging technique. Structure is observed which may be due to single excitation, double excitation and temporary negative ion states.